Solid protector against UV, process for its preparation and use thereof

ABSTRACT

PCT No. PCT/FI94/00232 Sec. 371 Date May 8, 1996 Sec. 102(e) Date May 8, 1996 PCT Filed Jun. 2, 1994 PCT Pub. No. WO94/28867 PCT Pub. Date Dec. 22, 1994A less dusty, more stable and more easily handlable protector against UV light than previously is obtained by supplying it in the form of solid particles having a mean diameter of at minimum 10  mu m and containing, dispersed in 90-20 parts by weight of wax, 10-80 parts by weight of a pigment which reduces the penetration UV light and is made up of metal oxide particles of a mean primary particle diameter smaller than 0.150  mu m.

The invention relates to a solid protector against UV light, comprisinga pigment made up of metal oxide particles reducing the penetration ofUV light and having an average primary particle diameter smaller than0.150 μm. Such solid protectors against UV light are used in thecosmetics industry. The invention also relates to the preparation anduse of such a solid protector against UV light.

The penetration of harmful ultraviolet radiation into the skin or othermaterial is prevented according to state-of-the-art technology by usingboth organic and inorganic protectors against UV radiation. InorganicUV-protectors include many very fine-grained metal oxides. Correspondingmetal oxides are in general also available in pigment grades, in whichcase they reflect or absorb mainly within the wavelength of visiblelight. Metal oxides protecting from UV radiation deviate from thesepigments in that they are transparent to the wavelength of visible lightbut, instead, reflect or absorb ultraviolet light. They are calledUV-pigments. The diameter of the primary particles of UV-pigments isclearly smaller than that of corresponding pigment particles (forexample, 0.1-fold), and the interface of their primary particles isconsiderably larger (for example 100-fold). UV-pigments are often alsocalled "microcrystalline" pigments of "micropigments".

Known inorganic UV-pigments include fine-grained titanium dioxides. Thediameter of their primary particles is in the order of 0.020 μm(0.010-0.100 μm), whereas the crystal size of pigment-grade titaniumdioxide is in the order of 0.200 μm (0.160-0.250 μm). UV titaniumdioxide can be prepared, for example, by the method of publicationEP-A-0 444 798 (Kemira Oy), by methods referred to therein, or by othermethods. UV titanium dioxide is available in anatase or rutile form orin amorphous form, and its particle shape is round, oblong orneedle-like. UV titanium dioxide is available both coated and uncoated,the coatings being either hydrophilic or hydrophobic.

Zinc oxide as a UV-pigment is known from the publication GB 21 84 356(Kao Corporation). Other known UV-pigments include oxides of cerium,zirconium and iron, having particle sizes below 0.150 μm and absorbingUV light. There are also known photochromatic UV-pigments in which theability to protect against light-increases under the effect of UVradiation (EP 526712, Kao Corporation).

Though UV-pigments, when dry, are at least partly agglomerated, theirparticle size is, nevertheless, so small that the products are highlydust-producing, from which there follow many drawbacks. The working ofsuch a very fine-grained UV-pigment into a well dispersed suspension isoften difficult.

The dust problem has been solved in patent publication GB 22 06 339(Tioxide Group PLC) with respect to UV titanium dioxide by grinding itin an oil phase with the help of an organic dispersing agent in a beadmill. A corresponding method for UV-zinc oxide is known from patentpublication EP-A 1-535 972 (Tioxide Specialties Ltd.).

However, the products thus obtained still have deficiencies, of which wemention limited storage stability, need for dispensing devices and fortransportation and storage containers, need to mix the stored product orproduct container, such as a barrel, before dispensing, as well asdifficulty of cleaning the said equipment and need to treat the wasteslurry produced in their washing. In general it is also necessary to addpreservatives to suspension-form UV-pigment dispersions in order tocombat microbial growth, even if it would be desirable to have theproduct keep entirely without preservatives, or at least withsubstantially smaller preservative doses.

Solid or semi-solid color pellets intended for cosmetics products areknown from patent publication PCT 93/00065 (Boots). This invention makesit possible to select a lipstick color from a large number of lipstickcolor shade alternatives by mixing equal-sized color pellets with an oilmixture, in a numerical quantity ratio indicated by a certain formula,and then by preparing lipsticks from these. The pellets contain a waxcomponent 1-50%, an oil or fat component 30-65%, and pigment ormother-of-pearl 10-35%. The pigments are color pigments conventionallyused in lipsticks, such as iron oxide, titanium dioxide, substratecolors, ultramarines, and organic colors. The use of UV-pigment is notspecifically mentioned; it is stated that, in addition to gloss controlagents, skin-calming agents, skin-care agents, vitamins, preservativesand antioxidants, the products may also contain sun-protectors.

The object of the present invention is to eliminate the problems of dustand stability mentioned above by providing a dust-free and stabile solidprotector against UV light, less susceptible to microbes, the protectorbeing based on the said metal oxide particles less than 0.150 μm in sizeand being mainly characterized in what is stated in the characterizingclause of claim 1. It has thus been-realized, that a dust-free andstable UV-protector is obtained if it is in the form of solid particles,having a minimum diameter of 10 μm and containing the said pigmentreducing the penetration of UV light, dispersed in 90-20 parts by weightof wax.

The pigment reducing the penetration of UV light used in the solidUV-protector according to the invention may be any pigment reducing thepenetration of UV light, the pigment being made up of metal oxideparticles having a mean primary particle diameter smaller than 0.150 μm.Typical usable metal oxide particles include the oxides of titanium,cerium, zirconium, iron, and zinc. The crystal form of the oxides mayvary greatly, but all of these metal oxides are characterized in thatthe mean diameter of their primary particles is smaller than 0.150 μm. Apreferred mean diameter of the primary particles is 0.010-0.100 μm, andthe most preferred in the order of approx. 0.020 m. It is also possibleto use photochromatic UV-pigments in which the ability to protectagainst light increases under the effect of UV radiation. Such pigmentshave been disclosed, for example, in publication EP 526 712, whichpublication is appended hereto as a reference.

As was pointed out above, the UV-protector according to the invention isobtained by dispersing 10-80 parts by weight of a pigment reducing thepenetration of UV light into 90-20 parts by weight of wax. By parts byweight is meant in this context the weight ratio between the pigmentreducing the penetration of UV light and wax, in which case there may bepresent any amount of other components, as long as the formedUV-protector will remain solid and in particle form. By the words"disperse" and "dispersion" is meant the maximally fine distribution ofat least one substance, in this case a pigment reducing the penetrationof UV light, into another, continuous phase, i.e. in this case wax. Bymaximally fine distribution is in this case also meant an evendistribution into the continuous phase, i.e. wax.

Preferably the proportion of the pigment which reduces the penetrationof UV light is at minimum 36% by weight, more preferably at minimumapprox. 40% by weight, and most preferably at minimum approx. 44% byweight, of the whole UV-protector. The UV-protector preferably containsthe said pigment which reduces the penetration of UV light in an amountof at maximum 85% by weight, more preferably at maximum 80% by weight,and most preferably at maximum 75% by weight.

As was pointed out, the solid UV-protector according to the invention isin the form of solid particles having a mean diameter of at minimum 10μm. In this manner there is obtained a dust-free, stable and easilyhandled material, which can easily be added to various products in whichit is used, such as cosmetic products. Preferably the UV-protectoraccording to the invention is in the form of solid particles having amean diameter of 30-5000 μm, preferably approx. 50-3000 μm. In thiscontext it is important to note that the solid UV-protector according tothe present invention differs from, for example, a solid UV-protectorcoated with wax or some other substance in that it is in the form ofsolid particles so large that the particle material is made up,dispersed in wax, of a pigment reducing the penetration of UV light.

The solid UV-protector according to the invention is thus made up of awax with a pigment reducing the penetration of UV light dispersed in it.Wax is the common name of substances which are waxy in their physicalproperties. By wax is in general meant a naturally and/or syntheticallyproduced substance the properties of which at 20° C. range from solidbut moldable to brittle and hard, from coarse to fine-grained, fromtransparent to opaque, but it is not glass-like. It melts withoutdecomposing at a temperature above 40° C., having a relatively lowviscosity even at a point somewhat above the melting or congealingpoint. Its solidity and solubility are often strongly dependent on thetemperature.

Waxes differ from other solid natural and synthetic products mainly inthat they usually melt and obtain low viscosity even within atemperature range of 50°-90° C., exceptionally up to a temperature of200° C. They usually burn evenly and give surfaces treated with them adurable sheen.

According to one embodiment of the invention, the wax is at roomtemperature a solid, waxy substance which becomes fluid at 40° C.minimum, preferably at 50° C. minimum, and most preferably at 55° C.minimum. On the other hand, according to one embodiment the wax is atroom temperature a solid, waxy-substance which becomes fluid at 200° C.maximum, preferably at 50° C. maximum, most preferably at 100° C.maximum. If the wax component according to the invention, or adispersion thereof and a pigment reducing the penetration of UV light,melts at a temperature below 40° C., it is necessary to use with thatwax other waxes or waxy components by means of which the meltingtemperature in the mixture dispersion can be raised to above 40° C.,preferably above 50° C., and most preferably above 55° C.

Waxes can be classified into natural waxes, which also include waxes ofmineral origin, and synthetic waxes, which also include chemicallymodified natural waxes.

Usable waxes according to the invention include those presented in theCRC Handbook of Chemistry and Physics, The Chemical Rubber Company, 53rdEd. 1972-3, page C-753. This work is appended hereto as a reference.Suitable vegetable waxes include carnauba, candelilla, Japan wax andjojoba wax; animal waxes include beeswax, spermaceti wax, and lanolinwax; and mineral waxes include paraffin wax, ceresin wax, ozocerite,montan wax, and microcrystalline waxes.

Synthetic waxes according to the invention include unsaponifiable waxesprepared from natural ester waxes by decarboxylation, syntheticallyprepared hydrocarbon waxes such as polyethylene waxes and/or propylenewaxes and polyethylene and polypropylene waxes modified by oxidation orby copolymerization with polar monomers, emulsifiable ester waxes formedfrom long-chain fatty alcohols and long-chain carboxylic acids,hydrogenated waxes obtained by hydrogenating drying oils such as castoroil, polyethylene oxide wax, polyethylene oxide/propylene oxide wax,phthalic imide wax and other waxy synthetic polymers, waxes made fromsaturated fatty acids by amide or imide condensation, and silicon waxes.

The waxes according to the invention also include waxy C₁₂ -C₂₄ chainsolid fatty acids, di- and polycarboxylic acids and correspondingalcohols, e.g. lauric, myristinic, palmitic, stearic, hydroxystearic,arachinic, behenic and erucic acids. Especially preferred natural waxesare carnauba wax, candelilla wax, jojoba wax, hydrogenated jojoba waxand Japan wax, beeswax, and/or lanolin. A preferred mineral or syntheticwax is paraffin wax. Other preferred waxes include cetyl palmitate,arachidyl behenate, behenyl erocant, pentaerythritol tetra-stearate,glycol-distearate, and cetostearyl stearate.

The wax used in a solid UV-protector according to the invention may alsobe a waxy surfactant, which include non-ionic waxy surfactants such asthe reaction products of fatty alcohols having 10-22 carbon atoms intheir alkyl chain, such as layryl, cetyl and stearyl alcohols, withethylene oxide (1-50 ethylene oxide units/alcohol), the fatty acidesters of ethoxylated fatty alcohols, ethoxylated glycerides such asethoxylated glyceryl monostearate, ethoxylated sterols and the like suchas ethoxylated cholesterol, and ethoxylated lanolin and its derivatives.Other waxes include anionic waxy surfactants such as the salts oflong-chain fatty acids and long-chain dicarboxylic acids, long-chainalkyl sulfates; polyethoxylated anionic surfactants such aspolyethoxylated alcohol sulfates, sodium cocoyl cetionate,polyethoxylated phosphoric acid esters; N-acyl sarcosinates;polyethoxylated phosphate esters; taurates; salts of fatty acid estersand hydroxycarboxylic acid esters, such as Na and Ca stearoyllactylates.

Further waxes include cationic, amphoteric or zwitterionic waxysurfactants and waxy salts formed by anionic and cationic componentswith each other. These include waxy phospholipids such as lecithin andits derivatives, imidazoline and betaine derivatives, alkyl amines, andalkyl ammonium compounds, polyethoxylated amines, and pyridinium salts.

Waxes used in a solid UV-protector according to the invention alsoinclude salts formed by anionic and cationic surfactants and polymerswith each other, used either without other waxy components or inmixtures with other waxy components. By means of such "ancat" compoundsit is possible to affect the structure of the wax and of the productsformulated from it and their adherence to a base, such as skin in thecase of cosmetic products. Such waxes can be prepared in different ways.

The following method is especially suitable for the preparation of saltsof anionic and cationic surfactants and polymers in the form of aninorganic salt. In the method, the anionic and cationic components aredissolved separately in water, whereafter the solutions are combined.The formed "ancat" salt is separated from the aqueous solution by asuitable procedure, for example by filtering or washing with water cleanof the initial components, or preferably by extracting in an organicsolvent, whereupon the inorganic counter-ions of the initial componentsremain in the aqueous solution. The organic solvent can be removed, forexample, by distillation.

In another method for the preparation of "ancat" waxes, the anioniccomponent and the cationic component are dissolved separately in asuitable solvent. The solutions are combined and the precipitated"ancat" product is separated, for example, by filtration.

Combination waxes of a basic wax component and an acid wax component mayalso be used. The components are either melted together, or they aremelted separately into another molten wax component, such as a melt ofparaffin wax or a surfactant, and are then combined.

According to one embodiment of the invention, the solid UV-protectorcontains wax at minimum 15% by weight, preferably at minimum 20% byweight, and most preferably at minimum 30% by weight. According to oneembodiment, the solid UV-protector according to the invention containswax at maximum 90% by weight, preferably at maximum 75% by weight, andmost preferably at maximum 63% by weight.

The dispersing of the UV-pigment into the melt of a waxy substanceaccording to the invention may preferably take place without specificdispersing agents, if the UV-pigment is coated with a coating agentespecially well suited for the medium used. In order to obtain amaximally homogenous dispersion it is often preferable to use a suitabledispersing agent. Its type depends on the properties of the wax used asthe medium, for example its polarity. When non-polar or only slightlypolar waxes were used as the medium, surprisingly good results wereobtained with W/O type emulsifiers. By means of these it proved to bepossible to disperse into wax both UV-pigments which had been pretreatedto make them hydrophobic and those pretreated to make them hydrophilic,both together and separately. This surprising observation is perhapsexplained in part by the fact that it is not necessary to require amolten dispersion to have as long stability periods in molten state asare required of a dispersion made in a liquid phase, such as an oil oraqueous phase. It is preferable to freeze a molten dispersion and togranulate it, without a long storage period, and thus the dispersion isobtained rapidly in a solid, storage-stabile form.

Examples of usable emulsifiers include the esters of alcohol or apolyhydroxide compound with fatty acids, e.g. fatty acids which contain8-22 C atoms and preferably at minimum 12 C atoms in their alkyl chain,such as solid or waxy esters of lauric, cetanic, and stearic acids withethylene glycol, polyethylene glycol, glycerol, polyglycerol, sorbitol,sucrose, pentaerythritol, and other polyols. Preferred emulsifiersinclude the mono- and diglycerides of such fatty acids, the sorbitolesters of the fatty acids and their ethoxylates, diacetylated fatty acidmonoglyceride tartrates, fatty acid lactylates, fatty acid polyglycerolesters, fatty acid propylene glycol esters, fatty acid sucrose esters,and the acetic acid, lactic acid, citric acid and tartaric acid estersof fatty acid monoglycerides. Especially preferred dispersing agentsinclude the monoglycerides of fatty acids containing at minimum 18 Catoms, and their acetic acid, lactic acid, citric acid and tartaric acidesters. Such emulsifiers are in general non-hazardous to theenvironment. They are usually of food grade, but are, nevertheless, notespecially vulnerable to microbial action.

Usable dispersing agents include A--B--A block polymers, B standing fora functional group or polymer capable of being adsorbed to the pigmentsurface and A for a polymer chain well soluble in the medium, ordispersing agents of the "comb polymer" type, which have secondarychains well soluble in the medium and affixed to a polymer chain capableof being adsorbed to the pigment surface. A chain soluble in moltenhydrophobic wax may in this case consist of, for example,polyhydroxycarboxylic acid or polymetacrylate and the chain adsorbing tothe pigment surface may consist of polyethylene oxide or polyacrylate ora polyacrylate-rich copolymer.

A suitable amount of dispersing agent, in case the pigment is notsufficiently well dispersible into the wax used without a dispersingagent, is approx. 0.5% by weight, preferably at minimum approx. 2% byweight, of the amount of the UV-pigment. At the upper limit of thedispersing agent amount the medium consists entirely of a waxyemulsifier and/or dispersing agent, in which case the solid dispersionis made up of 10-80 parts by weight UV of pigment in 90-20 parts byweight of waxy emulsifier or dispersing agent.

In one preferred embodiment of the invention the weight ratio of the waxto the waxy emulsifier and/or dispersing agent in solid UV-pigmentdispersions is approx. 50:1-1:1, preferably approx. 10:1-2:1.

According to one further embodiment of the invention, the waxyemulsifier and/or dispersing agent is made up of hydrophilic waxysurfactants which yield a solid UV-pigment dispersion. These includepolyethoxylated nonionic surfactants, such as the waxy reaction productsof fatty alcohols having 8-22 C atoms in their alkyl chain, such aslauryl, cetyl and stearyl alcohols, with ethylene oxide; the fatty acidesters of polyethoxylated fatty alcohols; polyethoxylated glycerides,such as polyethoxylated glyceryl monostearate; polyethoxylated alcoholand polyalcohol esters such as polyethoxylated propyleneglycolmonostearate, polyethoxylated glyceryl monostearate, polyethoxylatedfatty acid esters of sorbitan; polyethoxylated sterols and correspondingcompounds, such as polyethoxylated cholesterol and polyethoxylatedlanolin and their derivatives; solid block polymers of polyethyleneoxide and polypropylene oxide and solid polypropylene oxide/polyethyleneoxide derivatives of ethylene diamine, octyl or nonylphenylpolyethoxylates, taurates.

When a hydrophilic emulsifier and/or dispersing agent is used, apreferred weight ratio of wax to emulsifier is approx. 0:1-1:1.

The solid protector against UV according to the invention may, inaddition to a pigment reducing the penetration of UV light, wax, andpossible dispersing agent, also contain additives. Such additivesinclude color and mother-of-pearl pigments, melanin, radical scavengercompounds and vitamins, used either as admixtures or as powderingauxiliaries. It is also possible to add small amounts of oil or oilycosmetic auxiliary agents, as long as the lowering of the melting pointcaused by them is corrected by means of formulation.

The lowering of the melting point of a solid UV-protector according tothe invention can be inhibited by mixing in a wax which raises themelting point, such as a microcrystalline wax or, if the protectorcontains oil, a wax which binds oil well, such as ozocerite, or acomponent which reinforces the structure, for example an "ancat"compound such as mentioned above or a long-chain alcohol.

According to one preferred embodiment of the invention, the solidprotector against UV is a cosmetic, or it is used by precipitating it aspart of a cosmetic, in which case the pigment transparent to UV and thewax are cosmetically acceptable substances. One important viewpoint inthe invention is that new, easily handled products can be used forsatisfying the world's increasing need for cosmetic protectors againstUV light. According to one preferred embodiment, the UV-protectoraccording to the invention, which is at the same time a cosmeticsubstance or a component of a cosmetic substance, contains at least oneof the following cosmetic auxiliaries: a cosmetically acceptable organicprotector against UV, a cosmetically acceptable preservative, acosmetically acceptable antioxidant, and a cosmetically acceptableperfume. Typical protectors against UV include organic UV-protectorssuch as 4-aminobenzoic acid,NNN-trimethyl-4-(2-oxoborn-3-yldene-methyl)-anilinemethyl sulfate,homosalate, oxybenzone, 2-phenyl-benzimidazole-5-sulfonic acid and itspotassium, sodium and trimethanolamine salts,3,3'-(1,4-phenylenedimethydyn)bis(7,7-dimethyl-2-oxobicyclo)2,2,1(heptane-1-methanesulfonicacid) and salts, and 1-(4-tert.butylphenyl)-3-(4-methoxyphenyl)propane-1,3-dione. When the components of a solid protector against UVaccording to the invention are used, it should be borne in mind thatthey must be non-irritating and non-toxic and that they must fulfil therequirements set on cosmetic products in the legislation regardingcosmetic products. Methyl-butene parabene is an example of cosmeticpreservatives to be mentioned. Butylated hydroxyanisol is an example ofcosmetic antioxidants to be mentioned.

The invention also relates to a process for the preparation of any ofthe solid UV-protectors described above. An easily handled and practicalsolid protector against UV is obtained:

a) by dispersing into 90-20 parts by weight of molten wax 10-80 parts byweight of a pigment which reduces the penetration of UV light andconsists of metal oxide particles having a mean primary particlediameter smaller than 0.150 μm, and

b) by converting the molten or solid dispersion obtained from step a)into the form of solid particles having a mean diameter of at minimum 10μm. The ingredients usable in the process according to the inventionwere discussed above in connection with the description of the protectoragainst UV.

In the invention, the above-mentioned problems associated withUV-pigments are thus eliminated by formulating a solid protector againstUV in the form of solid particles by first dispersing, and possiblygrinding, a fine-grained UV-pigment at an elevated temperature intowaxes which are liquid at that temperature but solid at roomtemperature, and by then cooling and granulating the obtaineddispersion. In the preparation it is, of course, possible to use thekneading technique, in which case the raising of the temperature is notnecessary, as long as sufficient mixing time is used to ensure thedispersing of the UV-pigment.

A product prepared in the manner described above will not produce dust,and it is easy to store and use. It is a further advantage that the useof a specific dispersing agent is not always necessary for achieving astorage stabile concentrate. The wax medium is selected on the basis ofthe surface properties of the formulated pigment reducing thepenetration of UV light, the other components desired in the finalproduct, and the desired oil or water extension of the final product,and other factors.

The preparation of granules according to the invention, containingUV-pigment, takes place by dispersing the UV-pigment or pigments into amelted wax component, and by cooling and granulating the dispersion. Itis possible to use in the dispersing any device known from other pigmentdispersion processes. When the aim is the highest UV-pigmentconcentrations, it is advantageous to use slow-moving kneading devicesand roll mechanisms suitable for the dispersing of stiff mixes.Dispersing devices of high shear strengths or ultrasound devices aresuitable for more viscous mixes. The dispersing may also be carried outby using grinding devices, such as a bead mill. In the dispersion stepit is usually advantageous to use as an aid a suitable surfactant or asuitable combination of surfactants, preferably a mono- or diester ofglycerol. When the agglomerates of the UV-pigments have been divided,the dispersion is allowed to solidify either into large pieces, such assheets, pellets, tablets, extruder granules, or prills, which can, whenso desired, be converted into a smaller particle size by a known methodsuch as crushing, grinding or screening.

In one preferred embodiment of the invention, spray cooling is used forthe solidification, in which case the dispersion is obtained eitherdirectly or after possible pulverization and/or screening, in thedesired product form. Spray cooling takes place in the same manner ascurrently in other arts, such as the preparation of surfactants. Theapparatus includes an atomizer by means of which the molten dispersionis converted into droplets, and a chamber in which the drops congeal inso solid a form that they will not adhere to the base. It possibly alsoincludes a cyclone in which the product is separated from the gaseousmedium used in the cooling, the medium normally being air. Thetemperature of the cooling gas must be below the congealing temperatureof the melt, and may in general be close to the ambient temperature. Theapparatus may be a cylindrical container which has the atomizer in itsupper section and on the bottom of which the solidified particles willfall.

The atomizer may be a nozzle in which the molten dispersion is atomizedeither by pumping melt into the nozzle or by using as aid pressurizedgas, such as compressed air. Furthermore, the atomization can beeffected by a rapidly rotating dispersing device, such as a smooth orgrooved plate, a wheel disc or a blade wheel, or a perforatedcylindrical-surfaced prilling device. The molten dispersion is fed in atso high a temperature that the heat carried in it will suffice to keepthe temperature of the feeding device above the congealing temperatureof the melt dispersion, or the feeding device may also be equipped witha heating device, for example an electric resistor, hot-air blower, aliquid or steam mantle, etc.

The granules produced are preferably screened to the desired particlesize. To avoid agglomeration of the product during storage, the granulesmay be powdered with a fine-grained material such as silica or silicicacid. Another preferred powdering substance is UV-pigment, although itsefficiency in inhibiting agglomeration is usually not of the same orderas that of silica. The amount of powdering substance depends on thesoftness of the granule and on at how high a temperature the productmust be capable of being stored. A commonly used amount is approx.0.01-2% of the weight of the granule. It is often preferable to carryout the powdering while the granules are warm, for example close totheir maximum storage temperature.

Solid dispersions according to the invention may be turned into tabletsby using devices which are used for tabletting waxy substances. Inthese, the mix to be tabletted may, for example, be cast onto a cooledperforated belt or cylinder, where the tablet is formed, and they mayhave a cooled belt conveyor on which the tablet will have time toharden. The tablet size may vary greatly, but a size of approx. 4-5 mmis preferable.

The use of solid UV-protectors according to the invention for thepreparation of cosmetic formulations, such as sunscreen emulsions andcreams, lipsticks, and hair-care products takes place simply by heatingthem to so high a temperature that the solid UV-pigment dispersionmelts, whereupon it can be mixed with the other components to be used inthe formulation, in the same manner as the waxy substance used as themedium of the dispersion would even otherwise be used separately for thesaid application.

Except in cosmetic applications, granules according to the invention mayalso be used in coatings and plastics products to which UV-pigment isadded to improve their resistance to light. In these applications, theamounts UV-pigments used are usually small, for example 0.05-0.5% byweight. In UV-pigment granules according to the invention, intended forthese applications, it is preferable to use as the wax component waxesor softeners which are even otherwise used in the coating or plasticconcerned.

The following agents used in the examples are solid emulsifiersmanufactured by Grindsted A/S: Dimodan: monoglyceride, distilled;Lactodan: lactic acid ester of monoglyceride; Panodan: diacetyl tartrateof monoglyceride; Artodan: Na and Ca stearoyl lactates containing lacticacid 20-34%; Famodan: sorbitan ester of fatty acid; Emuldan:mono/diester of fatty acid.

EXAMPLES

In the formulae of the examples, all percentages refer to % by weight.The granule samples were prepared by the following methods.

Granulation Method 1

The waxy ingredients were mixed with each other and were melted byheating. UV-pigment was mixed in gradually. Then the mixture wasdispersed for 0.5-2 min by using a high-efficiency rod disperser,whereafter the obtained dispersion was poured onto a slab to cool intosheet form. The sheet was crushed and ground, was cooled, whennecessary, before grinding, and was screened to the desired particlesize.

Granulation Method 2

A molten dispersion was prepared as above, but the dispersing wascarried out in the course of approx. 15-30 min by using a circulardisperser blade. The molten dispersion was granulated in a rapidlyrotating atomizer into droplets, which upon cooling in air hardened intoround granules. The granules were screened to the desired particle size.

Example 1 A Nonionic Surfactant (Solan E)/hydrophilic UV--TiO₂

Into 200 g of molten PEG-75 lanolin (Solan E/Croda Chemicals, HLBapprox. 16) there was dispersed 170 g of UV--Titan M212 which had beengiven a hydrophilic surface treatment. The UV--TiO₂ concentration in themixture was 45.9%. The product was granulated with good results by bothmethod 1 and method 2. The functioning of the product was ascertained ina cosmetic preparation.

Example 2 UV--TiO₂ 64%, Solan E

Into molten PEG-75 lanolin (Solan E/Croda Chemicals) there was dispersedUV--Titan M262 which had been given a hydrophobic coating, whereupon theUV--TiO₂ concentration of the dispersion was 64%. The granulation was bymethod 1.

Example 3 Nonionic Surfactant Solan E/hydrophobic UV--TiO₂

Into 200 g of molten PEG-75 lanolin (Solan E/Croda Chemicals) there wasdispersed 170 g of UV--Titan M262 which had been rendered hydrophobic bya surface treatment. The UV--TiO₂ concentration of the mixture was45.9%. The product was granulated with good results both by method 1 andby method 2. The functioning of the product was ascertained in acosmetic preparation.

Example 4 Various Nonionic Surfactants

Solid dispersions containing UV--Titan M262 40% and UV--Titan M212 40%were prepared by method 1 in the following media: apropyleneoxy-ethyleneoxide derivative of ethylene diamine (Tetronic908), Poloxamer 338, Poloxamer 407, polyoxyethylene(20) tallow fattyalcohol and polyoxyethylene (50) tallow fatty alcohol. The meltviscosities obtained with the ethoxylated fatty alcohols were so lowthat these dispersions were assessed to be suitable also for granulationmethod 2.

Example 5 Surfactant Acidan-N12, Melting in a Microwave Oven

40 g of Acidan N12 (a citric acid ester of monoglyceride, HLB approx.11) and 40 g of UV--Titan were mixed while dry. 10 g of ion-exchangedwater was added. The mixture was melted in a microwave oven, most of thewater evaporating. The obtained viscous paste was stirred vigorously andwas poured onto a slab, on which it was shaped into a sheet approx. 3 mmthick. The sheet was hardened by cooling, was crushed, and was screenedwith a 1-mm mesh screen.

Examples 6a-6c

40 parts by weight of hydrophobic UV--Titan M262 was dispersed into 60parts by weight of a melt which had been prepared by heating together atapprox. 110° C. for approx. 20 min the following components: Marlophor T(waxy polyethoxylated alkyl ester of phosphoric acid), Noram S (waxyalkylamine) and paraffin wax.

Example 6a: Marlophor:Noram=2:1

Example 6b: Marlophor:Noram=1:1

Example 6c: Marlophor:Noram:paraffin wax=1:1:1.

The viscosities of the melt dispersions were so low that they wereassessed to be suitable for granulation by granulation method 2.

Example 7 "Ancat" 1

"Ancat" compound dodecyltrimethylammoniumdodecyl sulfate was prepared bydissolving separately in water equal molar amounts of sodium dodecylsulfate and dodecyltrimethylammonium bromide, by combining thesolutions, by extracting the "ancat" salt with diethyl ether, andfinally by evaporating the ether. The obtained fine-grained solidcompound was added to molten paraffin, into which it dispersed,increasing the viscosity of the melt even when used in a dose of a fewper cent.

Example 8 "Ancat" 2

An "ancat" compound was prepared by dissolving in diethyl etherseparately equal molar amounts of laurinic acid and dodecylamine. Bycombining the solutions a precipitate was obtained, which was separatedby filtration. The remainder of the solvent was dried off byevaporation.

The obtained fine-grained "ancat" salt was added on a hot plate intomolten paraffin, in which it dissolved well. The adding was continueduntil a 1:1 mixture with paraffin was obtained. Then UV--Titan M262 wasdispersed into this approximately 100° C. melt until a mixturecontaining UV--TiO₂ 45% was obtained, which mixture was cast onto a slabto form a sheet, which upon cooling was easily crushed into granules.

Example 9 "Ancat" 2, Further Experiment

The "ancat" compound of Example 9 was melted as such on a hot plate, andthe melt was heated to approx. 100° C. UV--Titan M262 was dispersed intothe melt until a mixture containing UV--TiO₂ 45% was obtained. Thismixture was cast onto a slab to form a sheet, which upon cooling waseasily crushed into granules.

Example 10 Wax+Cetyl Alcohol, No Dispersing Agent

A melt was prepared which contained 52 g of paraffin wax, 4 g of beeswaxand 2 g of cetyl alcohol (Crodacol C-90/Croda Chemicals). 42 g ofUV--Titan M262 was dispersed into the mixture.

The obtained dispersion was granulated by method 1.

Example 11 Dispersing Agent 14.7% Lactodan B30, Hydrophobic UV--TiO₂

360 g of paraffin wax, 30 g of beeswax, and 150 g of surfactant LactodanB30 were melted at approx. 100° C. Into this melt there was dispersed480 g of hydrophobic UV--Titan M262, whereupon the UV--TiO₂ content ofthe dispersion was 47%. The mixture was granulated by method 2, withgood results.

Example 12 Dispersing Agent Lactodan B30 20%, Various Wax Components

Different waxes were experimented with in granulation according tomethod 1. Good results were obtained with all of the formulae.

    ______________________________________                                                Example                                                                       12a  12b     12c     12d   12e   12f                                  ______________________________________                                        Lactodan B30                                                                            20     20      20    20    20    20                                 Paraffin wax                                                                            30     30      30    --    --    15                                 Beeswax    5     --      --    --    --    10                                 Carnauba wax                                                                            --      5      --    35    35    10                                 Candelilla wax                                                                          --     --       5    --    --    --                                 UV-Titan M262                                                                           45     45      45    45    --    45                                 UV-Titan M212                                                                           --     --      --    --    45    --                                 ______________________________________                                    

Example 13 Dispersing Agent Lactodan 1.8%; Testing in CosmeticPreparations

A molten approx. 80° C. UV--TiO₂ dispersion was prepared, whichcontained paraffin wax 48.2%, beeswax 3.8%, Lactodan B30 1.8%, andUV--Titan M262 46.5%. The mixture was dispersed by using an Ultra-Turraxdisperser and was granulated by using a cylindrical prilling devicerotating at 1400 r/min. Its 5 mm high cylindrical surface was equippedwith 0.7 mm diameter perforations, its 200 mm diameter lower surface wasclosed, and its upper surface was open in the center for the feeding inof the melt dispersion. The molten dispersion solidified in the airchamber into round particles having an average particle size of approx.0.5 mm.

Granules made according to the formula of Example 13, from whichparticles having a size greater than 0.83 mm had been removed byscreening, were tested for cosmetic preparations, with the followingresults:

The sun protection factor of a gloss lip-care rouge without the additionwas low, 3, and its UVA:UVB ratio was mediocre, 0.54. When granules(0.9% UV--TiO₂) in an amount of 2% were dispersed into the gloss rougemix, the value of the sun protection factor rose to 6 and the UVA:UVBratio to an excellent level, 0.69.

The sun protection factor of lipstick without the addition was mediocre,4-5, whereas with a granule amount of 4% (1.8% UV--TiO₂) the coefficientrose to a level of 16-19.

A sun-protector cream was prepared by using granules (4.9% UV--TiO₂) inan amount of 10.6%. The sun protection factor was at a level of 29-31.

Example 14 UV--TiO₂ 71%, Lactodan B30

Into a melt which contained 25 g of paraffin wax, 5 g of carnauba waxand 15 g of Lactodan B30 there was dispersed 110 g of hydrophobicallycoated UV--Titan M262, whereupon the UV--TiO₂ concentration in the mixwas 71.0%. After prolonged kneading at a low speed, a clear-surfacedhomogenous dispersion was obtained. Granules were prepared by method 1.

Example 15

UV--TiO₂ was dispersed into molten wax/emulsifier mixtures 15a)-15f).Dispersions were obtained the viscosities of which were suitable forboth granulation methods 1 and 2.

    ______________________________________                                                Example:                                                                      15a   15b    15c     15d   15e   f                                    ______________________________________                                        Lactodan P22                                                                            20      --     --    --    --    --                                 Artodan AM                                                                              --      20     --    --    --    --                                 Panodan AM                                                                              --      --     20    --    --    --                                 Famodan MS                                                                              --      --     --     5    --    --                                 Dimodan PV                                                                              --      --     --    --     1    --                                 Emuldan HA40                                                                            --      --     --    --    --     1                                 Paraffin wax                                                                            35      35     35    15    24    24                                 Carnauba wax                                                                            --      --     --    --     2     2                                 UV-Titan M262                                                                           45      45     45    45    23    23                                 ______________________________________                                    

Example 16a-16c

45 parts by weight of hydrophobic UV--Titan M262 was dispersed into meltmixtures which contained 46 parts by weight of paraffin wax, 4 parts ofbeeswax and 5 parts of the following emulsifiers:

Example 16a) Artodan CF 40

Example 16b) Artodan CP 80

Example 16c) Artodan NP 55

Well spreading melt dispersions were obtained, which were assessed to besuitable for both granulation methods 1 and 2.

Example 17 A Mixed Granule of Hydrophobic and Hydrophilic UV--TiO₂

Granules were prepared by using as the raw materials paraffin wax 23.8%,carnauba wax 4.8%, Lactodan B30 14.3%, UV--Titan M262 28.6%. andUV--Titan M212 28.6%. The UV--TiO₂ concentration in the mix was 57.2%.

Example 18 Compatibility of Hydrophobic and Hydrophilic UV--TiO₂

Granules were prepared by method 1 by dispersing 45 g of hydrophobicUV--Titan M262 into a melt consisting of 20 g of Lactodan B30 and 35 gof paraffin wax. Another batch of corresponding granules was prepared byusing hydrophilic UV--Titan M212. The mutual compatibility of thesegranules was tested by first mixing them together and by then meltingthis mixture. A well flowing, beautiful dispersion was obtained.

Example 19

The following UV-pigments were mixed with a 100° C. wax melt whichconsisted of mixtures of paraffin wax, beeswax and Lactodan B30 at theweight ratio 30:5:20:

Example 19a) UV--ZnO (Sachtotec LA 10)

Example 19b) UV--ZnO+UV--Titan M262 1:1

Example 19c) UV--Titan M262

The zinc oxide dispersed into the wax melt, forming a low-viscositymixture, whereupon the UV-pigment concentration in mixture a) was 50.3%by weight. The corresponding UV-pigment concentrations in mixtures b)and c) were 45% by weight. The mixtures were dispersed for 1 min bymeans of an Ystral rod disperser and they were cast into sheets. Thecooled sheets were crushed, were ground in a Philips coffee grinder, andparticles larger than 0.84 mm were screened off.

Example 20

The functioning of the granules of Example 19 was tested in a W/Osunscreen emulsion. The oil phase of the emulsion was made up of thefollowing components: Arlacel 780(PEG3/PPG2/-Glyceryl/Sorbitol/Hydroxystearate/Isostearate) 4.0 parts byweight, mineral oil 12 parts by weight, Miglyol 812 (Caprylic/CapricTriglyceride) 6 parts by weight, Crill 6 (Sorbitan Isostearate) 2 partsby weight, and UV-pigment granules in case a) 8.9 parts by weight and incases b) and c) 10.6 parts by weight. The aqueous phase of the emulsionconsisted of sorbitol 1.25 parts by weight, propylene glycol 1.25 partsby weight, Mg sulfate 0.7 parts by weight, and water in case a) 63.65parts by weight and in cases b) and c) 61.95 parts by weight. Both theoil phase and the aqueous phase were heated to 75° C. The aqueous phaseswere added to the oil phases gradually, while mixing. Finally 0.25 partsby weight of perfluoro-polymethyl-isopropyl ether (Fomblin HC/25) wasadded.

The functioning as a protector against UV light of these emulsions whichcontained UV-pigment approx. 5% by weight was tested, with the followingresults:

    ______________________________________                                        Sample   UV protection factor (SPF in vitro, FDA)                             ______________________________________                                        19a)     3                                                                    19b)     16-19                                                                19c)     17-20                                                                ______________________________________                                    

The granules 19b), containing UV--ZnO and UV--TiO₂, and the granules19c), containing UV--TiO₂, yielded excellent protection results. It canalso be seen that the result obtained with the combination granule 19b)was unexpectedly good as compared with the results obtained with thegranules 19a) and 19c), which contained only UV--ZnO or only UV--TiO₂.

Example 21

Solid dispersions were prepared from UV--Titan M160, which is a rutilepigment strongly surface modified with aluminum oxide and stearic acid.The pigment dispersed easily into ester waxes, such as carnauba wax, orinto mixtures of such waxes and paraffin waxes. The following soliddispersions were prepared:

    ______________________________________                                                  Example:                                                                      21a)       21b)   21c)                                              ______________________________________                                        Carnauba wax                                                                              50           25      5                                            Candelilla wax                                                                            --           25     --                                            Paraffin wax                                                                              --           --     50                                            UV-Titan M160                                                                             50           50     45                                            ______________________________________                                    

The dispersing was successful. Dispersions 21a) and 21b) were granulatedby method 1, dispersion 21c) by both method 1 and method 2.

Example 22

The solid UV--Titan M160 dispersion of Example 21c) was used for makinga test emulsion having a UV--Titan M160 concentration of 5%. The invitro sun protection factor measured for the preparation was 23-27 (FDA)and its UV-A/UV-B ratio 0.66. The dispersing was successful. Dispersions22a) and 22b) were granulated by method 1, dispersion 22c) by bothmethod 1 and method or alternatively dispersions 22a) and 22b) weretabletted.

We claim:
 1. A solid protector against UV light, comprising 10-80 parts by weight of a pigment and 90-20 parts by weight of a wax, wherein said pigment is made of metal oxide particles having a mean primary particle diameter smaller than 0.150 μm, reduces the penetration of UV light and is dispersed in said wax, and said protector is in the form of solid particles having a mean diameter of at minimum 10 μm.
 2. The protector against UV light according to claim 1, wherein the pigment reducing the penetration of UV light is made up of metal oxide particles having a mean primary particle diameter of 0.010-0.100 μm.
 3. The protector against UV light according to claim 1, wherein the pigment reducing the penetration of UV light is made up of titanium dioxide (TiO₂) particles or zinc oxide (ZnO) particles or a mixture thereof.
 4. The protector against UV light according to claim 1, wherein the protector contains at minimum 36% by weight of said pigment reducing the penetration UV light.
 5. The protector against UV light according to claim 1, wherein the protector contains at maximum 85% by weight of said pigment reducing the penetration of UV light.
 6. The protector against UV light according to claim 1, wherein the protector is in the form of particles having a mean diameter of 30-5000 μm.
 7. The protector against UV light according to claim 1, wherein the wax is a substance which is solid and waxy at room temperature and becomes fluid at a temperature of at minimum 40° C.
 8. The protector against UV light according to claim 7, wherein the wax is a substance which is solid and waxy at room temperature and becomes fluid at a temperature of at maximum 200° C.
 9. The protector against UV light according to claim 1, wherein the wax is a natural wax, a mineral wax, or a mixture thereof.
 10. The protector against UV light according to claim 1, wherein the wax is polyethoxylated alcohol or monoglycerol.
 11. The protector against UV light according to claim 1, wherein the protector contains at minimum 15% by weight of said wax.
 12. The protector against UV light according to claim 1, wherein the protector contains at maximum 90% by weight of said wax.
 13. The protector against UV light according to claim 1, wherein the protector is a cosmetic or constitutes part of a cosmetic, and the pigment transparent to UV light and the wax are cosmetically acceptable substances.
 14. The protector against UV light according to claim 13, wherein the protector contains at least one of the following cosmetic auxiliary substances: cosmetically acceptable organic protectors against UV light, cosmetically acceptable preservatives, antioxidants, vitamins and radical scavenger compounds, cosmetically acceptable color, mother-of-pearl and melanin pigments, and cosmetically acceptable perfumes.
 15. A method for preparing the solid protector against UV light according to claim 1, which comprises the following steps:a) dispersing 10-80 parts by weight of a pigment which reduces the penetration of UV light and is made up of metal oxide particles having a mean primary particle diameter smaller than 0.150 μm, into 90-20 parts by weight of a molten or viscous wax, whereby a molten or solid dispersion is obtained, and b) converting the molten or solid dispersion obtained from step a) into the form of solid particles having a mean diameter of at minimum 10 μm.
 16. The method according to claim 15, wherein said step a) of dispersing the pigment reducing the penetration of UV light into the wax is carried out with a kneading device or a roller mechanism if the wax is stiff, or a mixing device having a high shear speed or an ultrasound device if the wax is viscous, or a grinding device if a completely non-agglomerated pigment reducing the penetration of UV light is desired.
 17. The method according to claim 15, wherein said step a) of dispersing the pigment reducing the penetration of UV light into the wax uses as an aid a surfactant.
 18. The method according to claim 15, wherein said step b) comprises molding the molten or solid dispersion obtained from step a) into a form capable of being comminuted, hardening the molten or solid dispersion, when necessary, by cooling to below the congealing point of the wax, and comminuting the molten or solid dispersion by cutting, chopping, crushing or grinding.
 19. The method according to claim 15, wherein step b) comprises converting the melt obtained from step a) into drops, and solidifying the drops by cooling to below the congealing point of the wax.
 20. The method according to claim 15, further comprising c) screening the solid particles obtained from step b) to the desired size.
 21. The method according to claim 15, further comprising d) coating the solid particles obtained from step b) with a powder which inhibits agglomeration.
 22. The solid protector against UV light according to claim 1, wherein said protector is used as a component in cosmetic products.
 23. The protector against UV light according to claim 2, wherein the pigment reducing the penetration of UV light is made up of metal oxide particles having a mean primary particle diameter of 0.020 μm.
 24. The protector against UV light according to claim 3, wherein the pigment reducing the penetration of UV light is made up of titanium dioxide (TiO₂) particles.
 25. The protector against UV light according to claim 4, wherein the protector contains at minimum 40% by weight of said pigment reducing the penetration UV light.
 26. The protector against UV light according to claim 25, wherein the protector contains at minimum about 44% by weight of said pigment reducing the penetration UV light.
 27. The protector against UV light according to claim 5, wherein the protector contains at maximum 80% by weight of said pigment reducing the penetration of UV light.
 28. The protector against UV light according to claim 27, wherein the protector contains at maximum 75% by weight of said pigment reducing the penetration of UV light.
 29. The protector against UV light according to claim 6, wherein the protector is in the form of particles having a mean diameter of about 50-3000 μm.
 30. The protector against UV light according to claim 7, wherein the wax is a substance which is solid and waxy at room temperature and becomes fluid at a temperature of at minimum 50° C.
 31. The protector against UV light according to claim 30, wherein the wax is a substance which is solid and waxy at room temperature and becomes fluid at a temperature of at minimum 55° C.
 32. The protector against UV light according to claim 8, wherein the wax is a substance which is solid and waxy at room temperature and becomes fluid at a temperature of at maximum 150° C.
 33. The protector against UV light according to claim 32, wherein the wax is a substance which is solid and waxy at room temperature and becomes fluid at a temperature of at maximum 100° C.
 34. The protector against UV light according to claim 9, wherein the wax is paraffin wax, carnauba wax, candelilla wax, jojoba wax, Japan wax, beeswax, lanolin, or a mixture thereof.
 35. The protector against UV light according to claim 9, wherein the wax is hardened (hydrogenated).
 36. The protector against UV light according to claim 10, wherein the wax is an alcohol containing 12-22 carbon atoms in its chain, a polyethoxylated hydrogenated ricinic acid, a polyethoxylated lanolin, or a combination thereof.
 37. The protector against UV light according to claim 11, wherein the protector contains at minimum 20% by weight of said wax.
 38. The protector against UV light according to claim 37, wherein the protector contains at minimum 30% by weight of said wax.
 39. The protector against UV light according to claim 12, wherein the protector contains at maximum 75% by weight of said wax.
 40. The protector against UV light according to claim 39, wherein the protector contains at maximum 63% by weight of said wax.
 41. The method according to claim 17, wherein said surfactant is an ester of a fatty acid with glycol, glycerol, polyglycerol or sorbitol.
 42. The method according to claim 17, wherein said surfactant is a mono- or di-glyceride of a fatty acid, or an ester thereof with a small-molecule hydroxy acid.
 43. The method according to claim 19, wherein said solidifying step is achieved by spray cooling, which comprises atomizing the molten or solid dispersion into droplets, cooling the droplets in air or gas into solid form, and recovering the solidified droplets.
 44. The method according to claim 21, wherein said powder is silica or silicic acid.
 45. The method according to claim 21, wherein said powder is a pigment reducing the penetration of UV.
 46. The method according to claim 21, wherein the amount of the powder inhibiting agglomeration is 0.01-2% of the weight of the solid protector against UV light.
 47. The solid protector against UV light according to claim 22, wherein the cosmetic products are sunscreen creams, lip pomades, or hair-care products. 